Automated security and surveillance systems typically employ video cameras or other image capturing devices or sensors to collect image data. In the simplest systems, images represented by the image data are displayed for contemporaneous screening by security personnel or recorded for later reference after a security breach. In those systems, the task of detecting objects of interest is performed by a human observer. A significant advance occurs when the system itself is able to perform object detection and tracking, either partly or completely.
In a typical surveillance system, for example, one may be interested in tracking a detected object such as a human, a vehicle, or an animal that moves through the environment. Some existing systems include video analytics to automatically track moving objects. These systems typically provide on a display screen a colored outline box surrounding an image of a detected object. Some systems also include pan, tilt, zoom (PTZ) cameras that automatically zoom in on and follow a detected object as it moves through the camera's field of view. Some PTZ cameras use mechanically driven optics to zoom in on objects. These PTZ cameras, however, output standard resolution video (e.g., D1 resolution). The moving parts of PTZ cameras with mechanically driven optics tend to create significant failure and maintenance problems. The use of mechanically driven optics also results in a loss of a full view of a scene once the camera has zoomed in on an object. As a result, some systems include one camera to continuously capture the full view of a scene and a second camera to zoom in on detected objects. Two camera systems for one field of view are relatively expensive and difficult to install. For example, a two camera system requires complex set-up to calibrate X-Y coordinate locations from the fixed view camera to correctly drive the PTZ camera to zoom in on a desired location. Other PTZ cameras employ digital PTZ to zoom in on detected objects. However, the present inventors have recognized a number of drawbacks of conventional digital PTZ cameras.